Euler 15

gistfile1.txt

#!/usr/local/bin/node

// number of paths is a combination 40C20, because you have to get there in 40 steps and make 20 choices along the way
// that's n! / k! (n-k)!

n = 40;
k = 20;
nminusk = n-k;
n_factorial = 1;
k_factorial = 1;
nminusk_factorial = 1;

for(i=n;i>0; i--)
	{
	n_factorial*=i; 
	}

for (j=k;j>0;j--)
	{
	k_factorial*=j;
	}

for (l=nminusk;l>0;l--)
	{
	nminusk_factorial*=l;
	}
	
answer = n_factorial / (k_factorial * nminusk_factorial);	

console.log(n +"choose" + k + "is equal to " + answer);